Kai-Heng Feng reported that it takes long time (>1s) to resume Thunderbolt connected PCIe devices from both runtime suspend and system sleep (s2idle). These PCIe downstream ports the second link capability (PCI_EXP_LNKCAP2) announces support for speeds > 5 GT/s but it is then capped by the second link control (PCI_EXP_LNKCTL2) register to 2.5 GT/s. This possiblity was not considered in pci_bridge_wait_for_secondary_bus() so it ended up waiting for 1100 ms as these ports do not support active link layer reporting either. PCIe spec 5.0 section 6.6.1 mandates that we must wait minimum of 100 ms before sending configuration request to the device below, if the port does not support speeds > 5 GT/s, and if it does we first need to wait for the data link layer to become active before waiting for that 100 ms. PCIe spec 5.0 section 7.5.3.6 further says that all downstream ports that support speeds > 5 GT/s must support active link layer reporting so instead of looking for the speed we can check for the active link layer reporting capability and determine how to wait based on that (as they go hand in hand). Link: https://bugzilla.kernel.org/show_bug.cgi?id=206837 Reported-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> Tested-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> --- drivers/pci/pci.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 595fcf59843f..d9d9ff5b968e 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -4822,7 +4822,13 @@ void pci_bridge_wait_for_secondary_bus(struct pci_dev *dev) if (!pcie_downstream_port(dev)) return; - if (pcie_get_speed_cap(dev) <= PCIE_SPEED_5_0GT) { + /* + * Since PCIe spec mandates that all downstream ports that support + * speeds greater than 5 GT/s must support data link layer active + * reporting so we use that here to determine when the delay should + * be issued. + */ + if (!dev->link_active_reporting) { pci_dbg(dev, "waiting %d ms for downstream link\n", delay); msleep(delay); } else { -- 2.25.1
